[MLIR] Move eraseArguments and eraseResults to FunctionLike

Previously, they were only defined for `FuncOp`.

To support this, `FunctionLike` needs a way to get an updated type
from the concrete operation. This adds a new hook for that purpose,
called `getTypeWithoutArgsAndResults`.

For now, `FunctionLike` continues to assume the type is
`FunctionType`, and concrete operations that use another type can hide
the `getType`, `setType`, and `getTypeWithoutArgsAndResults` methods.

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D90363